Generally described, carbon dioxide (“CO2”) produced in power generation facilities is considered to be a greenhouse gas. As such, the carbon dioxide produced in the overall power production process generally is sequestered and then recycled for other purposes or otherwise disposed. In current integrated gasification combined cycle (“IGCC”) systems, the pre-combustion capture of carbon dioxide is preferred. Once captured, the carbon dioxide generally may be compressed before transport, disposal, or other use. Specifically, various integrated gasification combined cycle system designs require the compression of the carbon dioxide before the gas is recycled to, for example, the feed system, the gasifier, or other locations in the overall system.
The net power output from an integrated gasification combined cycle system or other type of power plant is determined by the output of the gas turbine engine(s) operating on a syngas or other fuel. Any parasitical electrical or other type of load in the power plant serves to reduce the net generation output. The compression of carbon dioxide, however, generally requires large amounts of auxiliary compression power. This compression power usually is provided by electric drives or steam turbines. This type of parasitic load thus results in lower overall power plant net output and efficiency. Moreover, the use of cooling tower water to cool the carbon dioxide compressors may be expensive and impractical in areas where water may be expensive and/or rare.
There is thus a desire for improved integrated gasification combined cycle systems. Such improved integrated gasification combined cycle systems may limit the parasitic load caused by compressing and cooling of carbon dioxide so as to increase net power generation output and efficiency while maintaining the ecological benefits of carbon dioxide sequestration.